Long-Term Debt (Detail Textuals 2) (USD $) In Millions, unless otherwise specified	12 Months Ended							1 Months Ended	12 Months Ended	1 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2008 Interest Rate Swap	Dec. 31, 2008 Letter of credit subfacility	Dec. 31, 2013 Letter of credit subfacility	Dec. 31, 2013 Revolving credit facility	Dec. 31, 2012 Revolving credit facility	Jan. 17, 2014 Revolving credit facility Subsequent Event	Dec. 31, 2012 Letter of swingline subfacility	Jan. 17, 2014 Letter of swingline subfacility Subsequent Event
Line of Credit Facility [Line Items]
Threshold limit of ratio of debt to earnings before interest taxes depreciation and amortization	no more than 2.5 to 1
Debt-to-EBITDA ratio (in times)	2.5
Threshold limit of ratio of earnings before interest taxes depreciation and amortization to interest expenses	no less than 2 to 1
EBITDA to interest expense ratio (in times)	2
Outstanding borrowings under the facility					$ 24.1	$ 53.3	$ 107.0
Amount of interest rate swap agreement			50.0	18.1
Debt instrument, interest rate, basis for effective rate				2.07%
Commitment fees and other debt related costs								0.7
Decrease in interest rates on the revolving loans under the Credit Agreement								0.125%
Maximum amount outstanding during the period		$ 350							$ 25	$ 35